Polycentric regions: Proposals for a new typology and terminology.

'Polycentricity on a regional scale', or in short the 'polycentric region' (PR), is a key concept in both urban and regional research and planning. But the term is used in many different ways, making it an overstretched concept unsuitable for drawing normative conclusions from. This article highlights the fact that, beyond the lowest common denominator – PRs consist of several centres ('poly' = many) and are situated on a regional scale ('region') – there is no single generally accepted definition of what a PR is. Instead, there are various historical trajectories for the formation of PRs, as well as different substantive perspectives. In this contribution, we will develop a conceptual typology and terminology describing the various dimensions of a PR for the North-Western European context on the basis of a critical literature review. The typology addresses two formation modes, four substantive perspectives and two time perspectives in an attempt to establish conceptual 'building block(s)' for use in empirical PR research and policy formulation. Our typology exposes knowledge gaps to be addressed in a recast PR research agenda. [ABSTRACT FROM AUTHOR]